Found some other articles on the one-tribe theory, though it appears to not be universally accepted:

African tribe populated rest of the world

The entire human race outside Africa owes its existence to the survival of a single tribe of around 200 people who crossed the Red Sea 70,000 years ago, scientists have discovered.

Research by geneticists and archaeologists has allowed them to trace the origins of modern homo sapiens back to a single group of people who managed to cross from the Horn of Africa and into Arabia. From there they went on to colonise the rest of the world.
Genetic analysis of modern day human populations in Europe, Asia, Australia, North America and South America have revealed that they are all descended from these common ancestors.
It is thought that changes in the climate between 90,000 and 70,000 years ago caused sea levels to drop dramatically and allowed the crossing of the Red Sea to take place.
The findings are to be revealed in a new BBC Two documentary series, The Incredible Human Journey, that traces the prehistoric origins of the human species.
Dr Peter Forster, a senior lecturer in archaeogenetics at Anglia Ruskin University in Cambridge who carried out some of the genetic work, said: "The founder populations cannot have been very big. We are talking about just a few hundred individuals."
(continued at link)http://www.telegraph.co.uk/science/science-news/5299351/African-tribe-populated-rest-of-the-world.htm